1. Field of the Invention
The present invention generally relates to heated fluid pipelines. More specifically, the present invention pertains to heated fluid pipelines that incorporate a hybrid insulation configuration.
2. Description of the Background Art
External thermal insulation is frequently an important component of heated pipelines including, without limitation, sulfur transportation pipelines. Generally, such thermal insulation is applied to provide adequate heat preservation and personnel protection for above-ground pipelines. Existing fluid transportation pipelines such as liquid sulfur transportation pipelines and/or piping systems often utilize high temperature insulation materials including, without limitation, the following: (1) aero gel insulation; (2) perlite insulation; (3) mineral wool; and (4) polyurethane insulation.
Aero gel insulation advantageously provides low thermal conductivity relative to commonly available high temperature insulations. Moreover, aero gel insulation is flexible and is easy to apply to pipelines. Because aero gel insulation provides low thermal conductivity, a thin layer of insulation may be utilized to coat and insulate a pipeline. Aero gel is typically expensive which makes it economically uncompetitive with other known insulation alternatives.
Perlite is another known insulation material. Perlite insulation is an inexpensive and proven insulation material with high compressive strength and high temperature capability. Perlite is fragile and may be damaged in transportation and installation. Perlite typically provides a low insulation value requiring additional thickness/material to achieve a desired heat profile.
Mineral wool is yet another known insulation material. Mineral wool is an economical insulation material used for high temperature applications. Mineral wool frequently provides better insulation value than perlite without high compressive strength to support a pipeline.
Polyurethane, another known insulation material, provides low thermal conductivity. Generally, polyurethane's insulation performance is exceeded only by aero gel insulation. Polyurethane insulation typically operates and/or insulates temperatures around 150° C. However, polyurethane insulation typically cannot directly withstand high temperatures such as those experienced in sulfur transportation lines.
It would be desirable to provide a system that addresses the limitations of conventional insulation materials while maximizing the advantages afforded by each of these insulation materials.